Fixed "Undefined property: stdClass::$page_namespace" error

* BacklinkCache::fullResultCache should always have all the columns
* Fixes bug from a9dc4d943e8f7e7824f31dc7fd1270873f8a9fdb

Change-Id: Ic0042ef6b1ce655bd97814362d95d8b0fe53affa
Merge "Fixed "Undefined property: stdClass::$page_namespace" error"